2017 Peterbilt 389 Battery Size, CCA & Group (Specs & Replacements)

As an ASE-certified master technician who has worked on countless heavy-duty trucks, I know that keeping a rig like the 2017 Peterbilt 389 starting reliably is critical for your livelihood. Whether you are running a Cummins ISX15 or a PACCAR MX-13 under the hood, these massive diesel engines require immense cranking power, especially in cold weather, alongside deep cycling capabilities to run cab accessories during your rest periods.

Below is the complete battery specification guide for the 2017 Peterbilt 389.

Quick answer: 2017 Peterbilt 389 Battery Specs

Here are the essential battery specifications you need to know before purchasing replacements:

• BCI Group Size: Group 31 (Requires a multi-battery setup, usually 3 or 4 batteries wired in parallel).
• Cold Cranking Amps (CCA): 925 to 1,150 CCA per battery (Totaling 2,775 to 4,600 CCA depending on the 3- or 4-battery configuration).
• Reserve Capacity (RC): 190 to 205+ minutes per battery.
• AGM vs. Flooded: Flooded is standard from the factory in many cases, but AGM is highly recommended if you run an APU, inverter, or have high "hotel loads" in the sleeper.
• Terminal Layout: Center-line threaded stud (usually 3/8"-16 stainless steel studs).
• Physical Dimensions (Group 31): Approximately 13.0" L x 6.8" W x 9.4" H per battery.
• Multi-Battery Setup: Yes, this heavy-duty diesel requires a parallel battery bank located in the step box. Always replace all batteries at the same time to prevent the older, weaker batteries from draining the new ones.

Replacement battery options

When outfitting a Class 8 truck like the 389, you cannot afford to skimp on quality. Here are top-tier replacement options commonly used in heavy-duty applications:

1. Odyssey Extreme Series (ODP-AGM31): A premium AGM battery offering massive cranking power (1150 CCA) and exceptional deep-cycle capabilities. Ideal for OTR drivers with heavy accessory use.
2. Optima YellowTop (D31T): Rated at 900 CCA, this AGM battery utilizes spiral-cell technology, making it incredibly resistant to the heavy chassis vibrations of a big rig.
3. Interstate Workaholic (31-MHD): A legendary flooded heavy-duty commercial battery providing 950 CCA. An excellent, cost-effective choice for day cabs or trucks with lower hotel loads.
4. ACDelco Gold (31900CT): A reliable conventional flooded battery outputting 900 CCA, featuring heavy-duty stud terminals for a secure fit.
5. DieHard Platinum AGM (Group 31): Offers around 1000 CCA and excellent vibration resistance with spill-proof AGM construction.

AGM vs flooded — which does this vehicle need?

While a standard flooded Group 31 battery bank will meet the OEM starting requirements for a 2017 Peterbilt 389, AGM (Absorbent Glass Mat) batteries are vastly superior for over-the-road trucks.

If you are running a sleeper cab with a microwave, refrigerator, TV, CPAP machine, or aftermarket inverter, AGM is highly recommended. AGM batteries handle deep discharges significantly better than flooded batteries and recharge faster. Additionally, they are completely sealed, meaning they won't spill acid or corrode your battery box cables as quickly, and they offer far better resistance to the intense vibrations generated by heavy-duty diesel engines.

Post-installation relearn / reset procedure

Unlike modern luxury passenger cars, the 2017 Peterbilt 389 does not utilize a strict Battery Management System (BMS) that requires a scan tool reset just to change the batteries. However, you still need to follow a basic post-installation procedure:

1. Clean All Connections: Wire brush all terminal rings, parallel jumper cables, and main grounds. Apply dielectric grease or anti-corrosion spray.
2. Check Inverter/APU Settings: If you have an aftermarket inverter or APU, you may need to reset the low-voltage disconnect settings, especially if switching from flooded to AGM.
3. Clear Ghost Codes: A sudden total loss of voltage during replacement can sometimes trigger intermittent fault codes in the ECM, TCM, or Bendix ABS modules. Cycle the ignition key a few times. If any dash lights remain, you may need to clear them using a heavy-duty diagnostic scanner (like JPRO).
4. Radio/Clock Reset: Be prepared to reset your cab’s clock and radio presets.

Signs of a failing battery

Don't wait until you're stranded at a truck stop in freezing weather. Watch out for these warning signs:

• Slow Engine Crank: The engine struggles or hesitates before turning over, particularly after sitting overnight.
• Low Resting Voltage: If your dash gauge reads below 12.2 volts before you start the truck, your battery bank is severely degraded.
• Inverter Cut-Off: Your cab accessories shut down prematurely because the batteries cannot sustain the load.
• Corrosion: Excessive white or blue acidic buildup on the threaded studs and parallel cables.
• Bulging Cases: A swollen battery case indicates severe overcharging or internal cell failure.

Common battery issues for this generation

For the 2017 Peterbilt 389, the most common battery-related issues stem from the parallel wiring harness and parasitic draws. Because 3 or 4 batteries are wired together, a single bad battery with a shorted cell will silently draw down the healthy batteries, killing the entire bank.

Furthermore, corrosion inside the battery jumper cables (the short cables connecting the batteries) can cause massive voltage drops. Technicians often see trucks where the alternator is charging properly, but due to bad jumper cables in the step box, the outer batteries are never fully recharged. Always inspect and replace these jumper cables if they are stiff or show signs of internal green copper corrosion.

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